1. Field of the Invention
The present invention relates to a process for regenerating a deactivated, carbon-covered, fine-grained, heat-resistant catalyst.
The invention relates in particular to a process for regenerating a fine-grained, heat-resistant suspension catalyst.
2. Discussion of the Background
The regeneration of catalysts, in particular suspension catalysts, which are used as fine particles for the catalysis of reactions of various types, is frequently extremely difficult. Reduction catalysts, such as Raney nickel, can generally only be regenerated by the metallurgical process. In contrast, oxidic catalysts can often be regenerated by burning off the deposited carbon and thus restoring, at moderate temperatures, the original surface and pore structure of the catalysts. However, such regeneration processes are frequently difficult to carry out due to the high reactivity of the finely divided components. Self-ignition and self-accelerating chemical reactions can occur if the regeneration is not precisely performed.
For example, during the preparation of 1,4-butynediol, an important precursor in the preparation of 1,4-butanediol, from acetylene and formaldehyde by the Reppe process, a catalyst has long been used which is essentially composed of copper oxide and bismuth oxide on a magnesium-silicate-based support. During use, this catalyst accumulates polymers and is thereby deactivated. This catalyst is conventionally regenerated to virtually completely restored activity by burning off the carbon coverings thus formed. However, during the regeneration, the fine-grained, dry, carbon-covered catalyst can self-ignite and dust explosions can occur.